Minor using parent's Apple Developer Account — whose SSN for App Store Connect banking and 1099-K?

Thanks for the post and welcome to the developer program.

We can't provide legal answers as the forums are for technical questions. I would recommend you to contact the developer account support at https://developer.apple.com/contact in case you need clarification on their documentation.

To join the Apple Developer Program to publish apps, you must be of the legal age of majority in your country or region. In most regions, this requires you to be at least 18 years old

It is important to know the country or region. All the information is here:

https://developer.apple.com/programs/enroll/

All the SSN will be depending on the owner of the account if you see the documentation above.

Adding users into an account:

https://developer.apple.com/help/app-store-connect/manage-your-team/add-and-edit-users

Legal requirements here: https://developer.apple.com/programs/terms/registered_apple_developer_20100301.p df

if you are the parent or legal guardian of individuals between the ages of 13 and the legal age of majority in the jurisdiction in which you reside, you may allow such individuals to share your Apple ID and password for their use solely under your supervision and only in accordance with this Agreement. You are responsible for such individuals’ compliance with and violations of this Agreement and any other Apple agreements

In all cases, welcome to the program hope to see your apps at the App Store soon. Please let us know if you need any technical help. I also recommend you to use Xcode instead of a 3rd party tool.

Albert  WWDR

Are you sure you really need a paid app? Realistically, you probably aren't going to make much money on your first app. The costs will almost certainly be more than any profits.

in App Store Connect, whose SSN should be entered — my mom's or mine? Or would it make more sense to obtain a free EIN (Employer Identification Number) from the IRS to use instead of either personal SSN?

If this is your mother's account, then all of the information would have to be hers. Furthermore, you should consider how much of this information is going to be posted on the internet.

If you want to distribute any paid apps in the EU, then you will have to be setup as a "trader" according to EU law. I'm pretty sure that means your mom's name, home address, phone number, and e-mail address will all be publicly visible in the EU. Don't do that.

a minor developer with a parent's account?

Just to clarify something here. Your mom will be the developer, with special authorization allowing you to share her developer account.

How did you handle the tax reporting correctly?

That depends on the tax laws where you live. I strongly recommend talking to an accountant just to get an idea of how this will impact tax requirements.

I have already spoken with a SCORE tax mentor who confirmed my mom will not be taxed

I guarantee that's wrong. All income is taxable pretty much everywhere in the world. There are certain special tax allowances for people running home businesses like this. But those allowances are strictly to reduce your compliance responsibilities to less-than-normal for a business. Tax always has to be paid.

Plus, there's more to worry about than just the tax. There's the compliance. You (your mom, actually) will have to fill out the correct tax forms. Depending on your family's situations, that could be cheap and easy, or exceptionally difficult, stressful, and cost thousands of dollars. It depends on your family. That's what an accountant can help you with.

Or, you can bypass all of that and stick to free apps for two years until you turn 18.